Thanks for the screenshots. Could you tell us the exact pixel size of the video you uploaded (width x height)? We measured a live header video on an iPhone 15 and an iPad, and both crop the way you'd expect if the video simply fills the frame. With a 3840x1646 video, that's about 18% of the width on each side on iPhone 15, close to the preview. Your iPhone 17 screenshot crops a lot more, so I'm wondering whether the file is a different aspect ratio.